Project Overview

Summary:

Overview

Dr. Nancy Rabalais at the Louisiana Universities Marine Consortium (LUMCON) was awarded an RFP-I grant at $12,185,000 to lead the GoMRI Coastal Waters Consortium (CWC) that consisted of 14 collaborative institutions and 188 research team members (including students). The goal of CWC was to improve society’s ability to understand, respond to, and mitigate the impacts of petroleum pollution and of related stressors on marine and coastal ecosystems, with an emphasis on the coastal and continental shelf of the Gulf of Mexico region. Researchers with CWC focused on 1) measuring the effects of stressors on aquatic and wetland soils, marsh plants, insects/spiders, fish, birds, commercial fisheries, and selected mollusk species; 2) determining the pelagic characteristics of adjacent open waters; researching continental shelf effects by examining the impacts on shelf hard banks, the phytoplankton community, and hypoxia (2010 focus); and 3) developing computational models of near-shore and estuaries transport.

Outreach

Over its award period (3 years, plus a 12-month no-cost extension), CWC organized more than 300 outreach activities or products, including but not limited to:

• CWC offered teacher workshops (e.g., “Beyond the Bay,” “Stalking the Seaside Sparrow”) targeting science development with a concentration on coastal and marine sciences. CWC provided teachers with remote operational vehicle (ROV) models, software, data analysis techniques, and other portable resources.
• To educate the public, CWC created a number of learning opportunities and resources, including adult workshops (Gulf Lagniappe), family events (e.g., “Family Day: Life Along the Edge”, “Dads and Daughters”), and the Marsh Edge-U-Cation Blog.
• The CWC Art and Science Camp for 8th-12th graders, during which students spent their days performing research and experiments about coastal wetlands and then translating what they learned into pieces of art.

Research Highlights

CWC research, which entailed over 430 sampling cruises or expeditions, resulted in 48 peer-reviewed publications, 213 scientific presentations and 125 datasets being submitted to the GoMRI Information and Data Cooperative (GRIIDC), which are/will be available to the public. CWC engaged 94 students over its award period. Significant outcomes of CWC research according to GoMRI Research Theme are highlighted below.

Theme 1: Physical Processes

• CWC researchers applied their finite volume coastal ocean model (FVCOM) to Barataria Bay. The FVCOM accurately reproduced the observed transport of oil slicks from the coastal waters into Barataria Bay and further determined that Mississippi River diversions were ineffectual in preventing oil movement into Breton Sound. They also applied wind-induced drift to the FVCOM to improve the accuracy of surface oil projections, as well as developed a highly efficient method to superimpose Lagrangian particle trajectories onto three-dimensional bathymetric charts.
• The FVCOM grid was extended into Barataria Bay and Breton Sound to test the efficacy of diverting water to keep oil from entering the estuaries. The test results indicated that the diversion to the east of the Mississippi River did not affect more than 30 km from the source and did not keep oil from entering.
• The FVCOM model is effective in simulating proposed restoration river diversions in mid Barataria bay and changes in water flow among the main distributary channels.

Theme 2: Chemical Processes

• The fate and composition of oil in wetland sediments across Terrebonne and Barataria bays over a 4-year period indicated that some hydrocarbon components (polycyclic aromatic hydrocarbons) were more resistant to degradation and may take ten years to revert to background levels, and that other hydrocarbon components (alkanes) were degraded more rapidly and expected to revert to background levels in five years. All fate and composition parameters are affected by resuspension and transport across marsh habitats, and the known high background levels of hydrocarbons in southeastern Louisiana waters.

Theme 3: Environmental Effects

• Many biogeochemical processes related to carbon, nitrogen, and phosphorus cycling and greenhouse gas exchange were studied by CWC researchers on paired oiled-unoiled plots across southeast Louisiana. They found methane flux to be higher (correlated with a reduction in methane oxidizing bacteria) and carbon dioxide and nitrous oxide fluxes to be lower in oiled plots. The variability in nitrification/denitrification, phosphorus sorption, and associated bacterial communities is high and more likely related to salinity gradients, flooding characteristics, physiography of the marsh, and sedimentary characteristics.
• Microbial community work since 2012 through 2015 indicated that there were distinctive marsh microbiomes that varied by season, flooding, salinity, vegetation type particularly along the marsh edge, but that the inland communities (e.g., 15 m) were more homogeneous.
• CWC researchers found that heavy oiling weakens the soil along the marsh-water interface, creating a deeper undercut of the upper 50 cm of the marsh edge and causing an accelerated rate of erosion that cascades along the shoreline. Simple measures of aboveground marsh vegetation alone may not be an appropriate indicator of recovery. Indicators of soil strength and microbial community composition more accurately define the health and structure of the marshes.
• Some nekton species behave differently in flume experiments with exposure to oil, and can avoid the oiled exposures. Differences in the in situ populations of marsh nekton, however, were not definitive for estimated oil exposure.
• Physiological stress was high in seaside sparrows immediately following the oil spill but has decreased with time.

Proposal Abstract - CWC I